The present scalpel was designed specifically for use in reconstruction of the anterior cruciate ligament in the knee. In this procedure, a strip of patellar tendon measuring between 10 to 12 millimeters in width is harvested from the middle of the tendon. The strip of tissue must be consistent in width to provide maximum strength in the resulting graft.
Current techniques for harvesting such strips of tissue require making two separate incisions in sucession, the second incision being guided by manually holding a ruler parallel to the first. This typically results in a graft that varies in width along its length. The differences in width from one point to another along the graft can range up to three millimeters.
When making sequential incisions along a tendon such as this, the tension within the tendon is modified after production of the first incision. The changes in tension affect the consistency of the second incision in a pattern that cannot be predetermined. It was recognized that if one could simultaneously produce the two incisions along opposite sides of the tendon, the tension encountered within the tendon would then be constant and not affect the width of the resulting strip.
The initial efforts to produce two parallel incisions that led to this development were accomplished by attempting to attach two conventional scalpels to one another in spaced parallel positions. While this constituted an improvement over the production of separate incisions, undersirable deviations in graft width continued to be encountered. Such variations in width are particularly difficult to prevent in the above-described surgical procedure, where the strip of patellar tendon is harvested along the middle of its underlying bone. The bony surfaces are curved and tend to splay two surgical blades outwardly from one another in response to the cutting pressures necessary to scribe the bone.
The present invention was developed in an effort to rigidly support two surgical blades for such procedures. It assures that sufficient pressure can be simultaneously applied to them to scribe underlying bone when this is required.